Concussions, otherwise known as Traumatic Brain Injury or TBI, are a major cause of morbidity and mortality in the US, and thus represent a public health issue that costs society money and lives. Of the 1.4 million who sustain some sort of TBI in the US annually, approximately 50,000 result in death, approximately 235,000 result in hospitalization, and approximately 1.1 million result in treatment from an emergency department. Among children up to 14 years old, TBI results in an estimated 2,685 deaths, 37,000 hospitalizations, and 435,000 emergency department visits annually (Source: Centers for Disease Control).
It has been estimated that 1,178,000 people play football in the United States (1.1 million in high school, 68,000 in college and 1,700 professionally). Over 100,000 concussions occur annually in all levels of football. An estimated 60% of TBI sustained in football are from head-to-head collisions. The average number of concussions sustained by NFL players was about 9 per week between 2009 and 2012.
A TBI occurs when a violent blow to the head causes the brain to slam against the skull beyond the ability of the cerebrospinal fluid to cushion the impact. As an example, when a football player sustains a blow to the head, the speeds of impact range from 17-25 mph with a force averaging 98 times the force of gravity. A study by the NFL revealed that most hits occurred from a blow to the side of the head, often to the lower half of the face, and to the forehead. When the players receive a blow to the head, a shock wave passes through the brain and bounces back off the skull. The initial blow may be due to linear (direct) impact or rotational (indirect) impact (FIG. 1). The concussion usually occurs at the opposite side of the point of impact. The impact may cause bruising of the brain, tearing of blood vessels, and nerve damage. The initial blow is termed the “coup” and the damage to the other side of the brain is termed the “contrecoup” or counter-blow, and this counter-blow often results in confusion, swelling, and blood clots. Additionally, rotational forces from angular blows may occur resulting in shearing and twisting of the brain within the skull (FIG. 2). (Sources: Mayoclinic.com, Biokinetics, Washington Post, Science Daily, kidshealth.org, Kaiser Permanente, Denver Post).
Many athletes sustain repeated traumatic brain injuries over the course of a playing career. Repeated concussions can cause Chronic Traumatic Encephalopathy (CTE). CTE is a progressive degenerative disease of the brain found in athletes (and others) with a history of repetitive brain trauma, including symptomatic concussions as well as asymptomatic sub-concussive hits to the head. The brain degeneration is associated with memory loss, confusion, impaired judgment, impulse control problems, aggression, depression, and, eventually, progressive dementia (Source: McKee et al., (2009) J. Neuropathol. Exp. Neurol. 68:709-35). Researchers at the Department of Veteran's Affairs brain repository have found evidence of a degenerative brain disease in 76 of the 79 former NFL players whose brains have been examined.
TBI in contact sports leagues like the NFL are a big and expensive problem. According to the online blog NFL Concussion Litigation, since the first official concussion lawsuit filed against the NFL in August 2011, nearly 250 other complaints against the NFL were filed through May 2013. In total, more than 4,500 players have filed suit against the NFL for concussion injury-related claims, most of them retirees.
Concussions typically occur when g-forces typically equal to or in excess of 100 g are applied to the head but may occur at lower g-forces. An extreme hit in the context of football may subject the player's head to g-forces approaching 150 g. As used herein the term “g-force” refers to the acceleration of an object relative to free-fall. As is typical in the art, the unit of measure g (also G), where for a stationary object on earth 1 g is equivalent to standard gravity (gn), 9.80665 meters per square second, an object has 0 g in a weightless environment such as free-fall or an orbiting satellite, and g-forces exceed 1 g on, for instance, accelerating rockets and roller coasters. As a point of reference, 100 g is about 10× the g force experienced by a fighter pilot in an F-16 during a jet roll. FIG. 3 illustrates the magnitude, position and direction of blows to the head sustained by a single college football player during the course of 1 season of games and practices at UNC. The player sustained 537 hits, 2 of which caused concussions (black lines). Note that the two that caused concussions were to the forehead and side of the face. These areas are most likely to be impacted by the helmet of another player. Another concentration of blows occurs to the back of the head, but these are primarily due to the back of the head hitting the ground rather than other players.
The traditional approach to reduce the number of concussion injuries has been to identify means to disperse, displace, and/or absorb some of the energy produced during helmet-to-helmet collisions. Typical commercially available protective helmets today consists of a polycarbonate shell with an internal liner. In this design, the hard outer shell distributes force away from the point of impact, while the liner, which is generally made of foam, pads, or air-filled cells, absorbs some of that impact energy. Although this general design is acknowledged for significantly reducing mortality on the playing field, the prevalence of concussions at all levels of play suggest that further design modifications are required. Consequently, helmet manufacturers have made structural and material modifications to the internal air-filled or foam-filled padding design that they claim are able to reduce the rate of concussions (FIG. 4). However, recent research has shown negligible differences in concussion rates among 1,332 high school football players wearing three different brands of helmets.
The most common method employed for diffusing impacts relies on air or foam-filled padding inside the helmet. FIGS. 4A-4C illustrate the typical design and padding configurations for three of the most common helmets sold commercially today.
In particular, FIG. 4A illustrates the interior view of the padding configuration of a commercially available football helmet (the Riddell Revolution Speed® football helmet). FIG. 4B illustrates the interior view of the padding configuration of a commercially available football helmet (the Schutt Vengeance® football helmet). FIG. 4C show the lateral view of a commercially available football helmet (the Xenith X1® football helmet), with the polycarbonate shell made transparent, to show the placement of 18 shock absorbers within the liner of the helmet. Common elements include: (1) facemask, on front of helmet (2) occipital features on back bottom of helmet, (3) chin guard and chin strap, (4) polycarbonate outer shell, (5) occipital (rear) padding array, (6) cheek pad, (7) frontal (forehead) padding array, (8) inner helmet lining to which padding is attached, (9) a standard air-cushion padding element, and (10) the space between the inner and outer helmet in which the padding elements are positioned.
The padding configurations illustrated in FIGS. 4A-4C provide protection to the frontal, temporal, and occipital part of the head and is representative of the padding configuration typically found in most helmet designs.
Helmet safety is rated by the National Operating Committee on Standards for Athletic Equipment (NOCSAE). Testing of helmets includes dropping them on rigs to test the ability of the helmet to withstand impact on the sides, front, back, and top of the helmet. The NOCSAE rating system comprises awarding 0-5 stars to specific helmet models, wherein 5 stars is the safest “best available”, 4 stars is “very good”, 3 stars is “good”, 2 stars is “adequate”, 1 star is “marginal”, and 0 stars is “not recommended.” (Source: STANDARD PERFORMANCE SPECIFICATION FOR NEWLY MANUFACTURED FOOTBALL HELMETS. NATIONAL OPERATING COMMITTEE ON STANDARDS FOR ATHLETIC EQUIPMENT (NOCSAE) DOC (ND)002-98m05 July 2005).
There are five established criteria for helmet modifications that must be considered when improving upon the current state of the art. In particular, (1) the design cannot affect the look, style and intensity of play; (2) the design should not dramatically affect the dimensions and look of the standardized helmet designed and accepted by NOCSAE; (3) the design should be able to be integrated in exist football helmet designs with little modification and within 1 to 2 years; (4) the design should be cost efficient and adaptable for play at all ages; and (5) the design should reduce the chance that the wearer will suffer a concussion. Additionally, it is desirable that any design improvements not significantly add to the weight of the helmet as this would become uncomfortable and cumbersome for the players.
Use of magnetic fields for the prevention and/or reduction of impact effects has been considered across a variety of fields where impact is frequent. For instance, magnetic fields have been used to prevent or reduce slamming or the over-closure of doors (see U.S. Pat. App. Pub. No.: 2013/0219658, which is incorporated by reference, in its entirety, into this application). Magnets have also been investigated for use in protective helmets. In particular magnetic repulsive forces have been disclosed for impact absorption in protective body gear, such as football helmets (see U.S. Pat. App. Pub. No.: 2013/0125294, which is incorporated by reference, in its entirety, into this application) and other team sports where contact is frequent or necessary to the game (see U.S. Pat. App. Pub. No.: 2014/0215693, which is incorporated by reference, in its entirety, into this application).
To date, however, magnets have not been properly incorporated in protective helmet technology to decelerate impact, reduce collision forces, and mitigate neck injuries stemming from laminar motion and the sticking together of helmets—both of which would be caused by magnet configurations described in the prior art. In some instances, the existing helmets comprising magnets do not differentiate between coup and countercoup injuries, and described helmet designs would not mitigate both coup and countercoup injuries. For example, the prior art helmets employ a system of spaced small magnets in “cells” between the inner and outer shells of the helmet, which act in the same way as traditional helmet padding. These cells would cushion a blow to the head, however, due to their small size, they may not decrease the actual impact velocity from a second identical helmet in a collision.
In other instances, the magnets in existing helmets are attracted to one another's sides when incorporated into a helmet design without magnetic shielding or improperly configured. Such designs caused the helmets to stick together at some angles of impact and/or caused laminar motion between two opposing helmets.
In particular, existing helmets have magnets configured such that they act solely to repulse another identically configured magnetic helmet, neither providing any protection from the counter-coup that results from an impact which may occur nor protection from a near-uniform repulsive force around the head of the wearer of the helmet. Such is not an optimal design for prevention of TBI, and actually would cause rotational energy to be applied to the neck of the wearer due to the shape of the magnetic field. It will be appreciated by anyone who has experimented with magnets that when one forcefully slams together two magnets in a N—N or S—S configuration, the magnets do not just repel one another; due to the shape of the magnetic field, the magnets quickly change direction and “slide” off of one another. The conversion of a nearly linear impact vectors to a different vector as the helmets come into proximity with force is not a problem in the lab. However, when the helmets are secured to human heads, the rapid change in vector can result in significant twisting/rotational force on the neck, causing muscular injury, injury to the cervical spine, and/or potentially injury to the spinal cord if the cervical spine is damaged significantly. Consequently, alternative approaches to diffuse impact energy need to be conceived.
The helmet described herein solves these unanticipated problems by modifying the spatially modulated magnetic fields (SMMF) of the magnetic elements (which may otherwise be referred to as magnets in the context of this specification). Methods to modify the SMMF can include ferromagnetic shielding, grouping of magnetic elements, and use of Halbach arrays. Therefore the helmet described herein comprises a substantially improved design over the prior art and will prevent head injuries without inducing neck injuries due to serious design flaws.